RESUMEN
Chrysomycin A is one of the valuable drug leads used to treat infectious diseases such as tuberculosis and methicillin-resistant Staphylococcus aureus. In order to increase its yield, this work firstly focuses on optimization of fermentation conditions and medium compositions of a wild-type chrysomycin A-producing strain Streptomyces sp. 891 from marine sediment. By single-factor experiment, effects of fermentation conditions (fermentation time, seed age, initial pH, inoculum amount, liquid loading, shaking speed) and medium composition (carbon sources, nitrogen sources, inorganic salts) on the yield of chrysomycin A were carefully evaluated and analyzed followed by optimization at shake-flask level. The results indicated its optimal fermentation conditions for producing chrysomycin A were as follows: fermentation time 168 h, seed age 48 h, initial pH 6.5, inoculum amount 5.0%, liquid loading 30 mL in 250-mL Erlenmeyer flask and shaking speed 220 rpm. By orthogonal test, the optimal fermentation medium constitutes 40 g/L glucose, 20 g/L corn starch, 25 g/L hot-pressed soybean flour, 3 g/L CaCO3. Verification tests suggested the yield of chrysomycin A under optimized conditions reaches up to 3648 ± 119 mg/L, which is increased by almost 5 times. These findings definitely pave the way for scale-up preparation of chrysomycin A and application in the pharmaceutical industry.